1. Field of the Invention
The present invention relates to a maintenance operation method for a wind turbine generator including an induction generator and a phase advance capacitor, and a wind turbine generator thereof. In particular, the invention relates to a maintenance operation method for a wind turbine generator including a tower provided to stand on the ground or on the water, a nacelle supported on the tower to be controlled to rotate in the yaw direction, and a plurality of rotatable blades with blade pitch control provided to the nacelle, wherein a power factor of a induction generator can be improved, and a wind turbine generator thereof.
2. Description of the Related Art
In recent years, the use of a wind turbine generator to generate renewable energy has become popular in view of environmental preservation.
A large size wind turbine generator often adopts the so-called a nacelle type wind turbine generator comprising a rotor head equipped with blades, a nacelle for accommodating a drive train and a generator, and a tower for supporting the nacelle. The drive train is for transmitting a torque from the rotor head side to the generator side, and usually includes a speed increasing gear so that rotational speed of the rotor head is increased to transmit to the generator
In this type of wind turbine generator, an induction generator has been in general use. However, a power factor control cannot be performed because the operation power factor is decided corresponding to the output power of the generator. Therefore, in the conventional generator, a phase advance capacitor is parallel-connected to the power output line 5 so as to improve the lagging power factor of the power output.
For example, Japanese Unexamined Patent Application Publication No. H11-41990 (Patent Publication 1) shows a construction in which a plurality of the power generator units are arranged in parallel, and each of the power generator units includes a phase advanced capacitor connected to an output line of the power generator via a magnetic switch, respectively, wherein the number of the connected phase advanced capacitor is increased according to decline of the total power output so that a power factor of the power output is controlled to keep a constant value. Japanese Unexamined Patent Application Publication No. 2006-109568 (Patent Publication 2) shows a construction in which a linkage device is inserted in an output line connecting an induction generator and a distribution system, wherein the linkage device includes a contactor for linking the induction generator with the distribution system, wherein the phase advance capacitor is connected via a switching element to the output line between the contactor and the distribution system. According to the construction described above, the phase advance capacitor is connected to the output line before the contactor is turning ON, thereby controlling the voltage fluctuation.